The objectives of this proposal are to document and characterize the "insulin" or insulin'like immunoreactivity in the pituitary gland, determine the distribution of "insulin"-producing cells, test the effects of glucose and various hormones on in vitro pituitary "insulin" production, survey genetically diabetic rodent strains and drug-induced diabetic rodents for possible changes in the distribution of "insulin"-producing cells in the pituitary and investigate human pituitary tissue to determine if "insulin"-producing cells are present. We plan to characterize the "insulin" or insulin-like immunoreactivity in normal and diabetic rodents and in human pituitary tissue by analysis of the transcript with Northern analysis of anterior pituitary mRNA, isolation of an insulin-hybridizing clone from a rodent pituitary cDNA library by analysis of the immunoreactive protein using immunoprecipitation followed by electrophoresis of radiolabeled translation products in addition to protein sequence analysis. Histochemical characterization will be made with in situ DNA-RNA hybridization and immunocytochemistry on sections of pituitary tissue and on pituitary cells in culture. The distribution of "insulin"-producing pituitary cells in normal and genetically diabetic and chemically-induced diabetic rodents will be compared using in situ hybridization and immunocytochemistry. Sections of human pituitary and where possible, cultured human pituitary cells will be surveyed using human insulin cDNA and other probes and with immunocytochemistry to determine if insulin-producing cells are present. If such cells exist, we plan to search for possible pathological changes in diabetics.